1. Field of the Invention
The present invention relates generally to an electromagnetic-induction system, and more particularly, relates an electromagnetic-induction system with the optimum antenna layout and the method for forming the same.
2. Description of the Prior Art
Because a handwriting recognition system could replace the mouse, and is more suitable than the mouse to let the user input words and patterns by user's hands, improvement of the handwriting recognition system is a hot and important field of current computer technology. The original intention of the handwriting recognition system is to replace the mouse. As usual, to enhance the user's convenience, a handwriting recognition system would usually replace the mouse by both wireless pen and tablet. Herein, the pen nib of the wireless pen usually corresponds to the left button of the mouse. Conventional handwriting recognition systems have been developed for many years, but these products are applied to perform only one function, such as drawing or inputting a word.
In the conventional electromagnetic-induction systems, there are usually a digitizer tablet and a transducer/cursor in the form of a pen or a puck. As is well known, there are two operation modes for determining the position of a pointing device on the surface of a digitizer tablet, wherein one is a relative mode, and the other is an absolute mode. A mouse device operates in a relative mode. The computer sensing the inputs from a mouse recognizes only relative movements of the mouse in X and Y directions as it is slid over the surface on which it is resting. If the mouse is lifted and repositioned on the surface, no change in the signal to the computer will be detected. A common approach uses a sensing apparatus inside the mouse to develop a pair of changing signals corresponding to the longitudinal and transversal movements of the mouse. On the contrary, a cursor device in a digitizer tablet system, such as electromagnetic-induction pen, operates in an absolute mode. If a cursor device is lifted and moved to a new position on its supporting surface, its signal to a computer will change to reflect the new absolute position of the cursor device. Nowadays, various methods have been used to determine the position of a cursor device on the surface of its supporting tablet, wherein one common skill which is applied for the absolute mode is electromagnetic field sensing.
Early transducer/cursors were connected to the tablet by means of a multi-conductor cable through which the position and button/pressure information are transferred virtually without any problem. The cordless transducer/cursors in some of the prior arts have attempted to use frequency and/or phase changes to transmit the non-positional status of the transducer/cursor functions such as buttons pushed, pen pressure, or the like. However, if there is no sophisticated processing, frequency and phase changes are very prone to false reading resulting from several outside factors such as metal objects, noise, wireless electromagnetic wave and so on. These problems become more apparent, especially in a larger digitizer tablet. Improvements have also been made in the prior arts to allow a user to use pointing devices on a digitizer tablet system in dual modes of operation that can provide information of either a relative movement or an absolute position under the control of the user. Usually, a handwriting recognition system is a device with cordless pressure-sensitivity and electromagnetic-induction. Conventional antenna layout for the electromagnetic-induction system is shown in FIG. 1A, each antenna loop 110 having a antenna address is connected with the same connector 120. In general, the pin of each antenna loop 110 is arranged according to the antenna addresses with regulated arrangement, such as X1, X2, X3 . . . , the arrangement table as shown in FIG. 1B, and each antenna loop 110 consists of a plurality of n-type sections, wherein the path of the antenna loop 110 formed by the plurality of n-type sections is extended from the connector 120 until the ground 130 such that the region surrounded the path of the antenna loop 110 takes shape as a region with H-shaped profile. However, this antenna layout makes each antenna loop to go across each other, it is called “across-line effect”, such that the antenna layout is designed to be over tight squeeze, as shown in FIG. 1C, and it results in some problems, especially, the noises are substantially raised due to foregoing defects. Furthermore, the product's dimension is shrunk to conform to the requirement of the design rule in the present industry so it is necessary that all devices and the antenna loops in the antenna layout of the electromagnetic-induction system is becoming more and more smaller. Especially, in the antenna layout with multi-loops, its design of loops is becoming disorderly, complex and highly concentrated more and more, such that the across-line effect about these loops is more serious. On the other hand, the peripheral region of the antenna-board is also difficult to be shrunk because all antenna loops are integrated in the same connector. Moreover, when the antenna process for designing the antenna layout with smaller dimension is performed, it is extremely easy to result in the short circuit due to complex across-line design. Therefore, the antenna layout for the electromagnetic-induction system has been difficult to overcome the critical dimension in the antenna process for fabricating the antenna layout with multi-loops, and it would not achieve the subject matter for shrinking the dimension of the antenna layout with multi-loops. In view of the above-mentioned reasons, this invention provides an optimum antenna layout of the electromagnetic-induction system to reduce the across-line effect in the design rule, so as to effectively prevent the various problems resulted from shrink of the antenna layout and strengthen the efficiency of electromagnetic-induction system.